Project description:The mitochondrial enzyme ALDH1B1 is upregulated in colorectal and pancreatic adenocarcinomas and promotes tumor growth. Using both genetic and chemical perturbations, we have characterized the ALDH1B1-regulated transcriptome in a colorectal cancer cell line. Genes induced by ALDH1B1 include those related to mitochondrial metabolism, stemness, and ribosomal function. These findings implicate ALDH1B1 in cancer metabolism and cancer stem cell maintenance, and they underscore the potential of ALDH1B1 as a therapeutic target.
Project description:Metastasis is the leading cause of cancer-related mortality. Cancer stem cells contribute to metastasis in the murine colon cancer models, but the underlying mechanisms are unclear. Here we report a Wnt ligand, Dickkopf2 (DKK2) is essential for colorectal cancer stemness. Genetic depletion of Dkk2 in intestinal epithelial or stem cells reduced tumorigenesis as well as expression of the stem cell marker gene Lgr5 in a model of colitis-associated cancer. Mechanistically, DKK2 activates c-Src followed by increased LGR5 expressing stem cells in colorectal cancer through degradation of HNF4α1. Splenic injection of DKK2-deficient cancer organoids into C57BL/6 mice resulted in a significant reduction of liver metastases compared to the control cancer organoids in spite of the presence of oncogenic mutations in Apc, Kras and Tp53 genes. These findings suggest that DKK2 is required for stemness of colorectal cancer cells, which in turn contributes to metastasis.
Project description:Canonical Wnt signaling output is mediated by β-catenin, which interacts with LEF/TCF transcription factors and recruits a general transcriptional activation complex to its C-terminus. Its N-terminus binds BCL9/9L proteins, which bind co-activators that in mammals contribute to fine-tuning the transcriptional output. We found that a BCL9/9L-dependent gene expression signature was strongly associated with patient outcome in colorectal cancer and that stem cell and mesenchymal genes determine its prognostic value. Abrogating BCL9/9L-β-catenin signaling in independent mouse colorectal cancer models resulted in virtual loss of these traits, and oncogenic intestinal organoids lacking BCL9/9L proteins proved no longer tumorigenic. Our findings suggest that the BCL9/9L arm of Wnt-β-catenin signaling sustains a stemness-to-differentiation equilibrium in colorectal cancer, which critically affects disease outcome. Mutational activation of the Wnt pathway is a key oncogenic event in colorectal cancer. Targeting the pathway downstream of activating mutations is challenging, and the therapeutic window is limited by intestinal toxicity. Contrasting with phenotypes caused by inactivating key Wnt pathway components, ablation of BCL9/9L proteins in adult mice indicated that they were dispensable for intestinal homeostasis, consistent with their role in tuning transcription. Cancer stem cells are increasingly recognized as responsible for tumor recurrence. The correlation between stemness traits in colorectal cancer models and BCL9/9L-β-catenin signaling suggests that high Wnt signaling output is required for their maintenance. Our findings suggest that pruning Wnt-β-catenin signaling might be well tolerated and prove sufficient for trimming stemness traits and improving disease outcome. Examination of Bcl9/9l-knockout versus wild-type transcriptome in murine AOM-DSS tumors, APC-Kras tumors and healthy colocyte extracts.
Project description:Cancer stemness represents a major source of development and progression of colorectal cancer (CRC). c-Met critically contributes to CRC stemness, but how c-Met is activated in CRC remains elusive. We previously identified the lipolytic factor ABHD5 as an important tumour suppressor gene in CRC. Here, we show that loss of ABHD5 promotes c-Met activation to sustain CRC stemness in a non-canonical manner. Mechanistically, we demonstrate that ABHD5 interacts in the cytoplasm with the core subunit of the SET1A methyltransferase complex, DPY30, thereby inhibiting the nuclear translocation of DPY30 and activity of SET1A. In the absence of ABHD5, DPY30 translocates to the nucleus and supports SET1A-mediated methylation of YAP and histone H3, which sequesters YAP in the nucleus and increases chromatin accessibility to synergistically promote YAP-induced transcription of c-Met, thus promoting the stemness of CRC cells. This study reveals a novel role of ABHD5 in regulating histone/non-histone methylation and CRC stemness. We used microarrays to detail the gene expression of HCT116 colon cancer cell and ABHD5 knockdown HCT116 cell.
